1. Field of the Invention
This invention relates to plasma display panel drive method and apparatus, and particularly to plasma display panel drive method and apparatus which is capable of preventing an generation of contour noise and making to be high a brightness level.
2. Related Art of the Invention
Recently, there have been actively developed the plasma display panel, hereinafter PDP, which facilitates to manufacture it and to implement a large screen. The PDP uses conventionally a gases discharging phenomenon and allows a picture to be displayed by visible rays emitted from a fluorescent material which becomes in a emitting light by vacuum ultraviolet rays generated at the gases discharge.
Referring to FIG. 1, there is shown a discharging cell 30 included in the PDP of an alternating current system having three electrodes. The discharging cell 30 includes an upper glass substrate 10 loaded with a sustaining electrode pair thereon and a lower glass substrate 20 loaded with an address electrode 22 thereon. The upper glass substrate 10, which is used as a face for displaying the picture, is arranged in parallel with the lower glass substrate 20 by a barrier rib (not shown), as shown in FIG. 1. The sustaining electrode pair consists of a scanning/sustaining electrode 14 and a sustaining electrode 16 formed side by side on the upper glass substrate 10. An upper dielectric layer 12 and a protective layer 18 are sequentially coated on the upper glass substrate 10 formed with the scanning/sustaining electrode 14 and the sustaining electrode 16 thereon. The address electrode 22 is formed on the lower glass substrate 20 to intersect with the sustaining electrode pair in perpendicular. On the lower glass substrate 20 having the address electrode 22, there are sequentially formed a lower dielectric layer 24 and a fluorescent material layer 26. Finally, a discharging gas is injected into a discharging space 28 provided by the barrier rib.
The discharging cell 30 having the structure as described above is selected by an address discharge caused between the address electrode 22 and the scanning/sustaining electrode 16. In the selected discharging cell 30, a sustaining discharge is caused between the scanning/sustaining electrode 14 and the sustaining electrode 16 to generate the vacuum ultraviolet rays. The vacuum ultraviolet rays allows the fluorescent material 26 to become in the emitting light, thereby generating the visible rays. Such a PDP of the alternating current system controls the number of the sustaining discharge to realize a stepwise brightness, i.e., a gray scale. The number of the sustaining discharge is recognized by users and manufacturers as an important factor determining the brightness of the PDP and a discharge efficiency. Actually, a rectangular pulse having the frequency of 10 KHz to 100 KHz is applied to the PDP of the AC system in order to perform the sustaining discharge. In this case, the sustaining discharge is generated once per sustaining pulse in a moment. Also, charged particles generated at the sustaining discharge move along with the polarity of the electrode on the discharging path formed between the sustaining electrode pair, thereby creating spatial electric charges into the discharging space of the cell 30. The sustaining discharge can not be maintained since the discharging voltage into the discharging space drops down to the voltage lower than a discharging start voltage due to the spatial electric charges. Consequently, in the PDP of AC system using the sustaining pulse, the discharging efficiency becomes low because the sustaining discharge is generated once in a moment per sustaining pulse.
To solve such a disadvantage in the PDP of the AC system, there is developed a PDP of radio frequency (RF) system. The PDP of RF system includes discharging cells as shown in FIG. 2. The discharging cell of FIG. 2 includes a RF electrode 42 formed on the below face of an upper substrate 40, a data electrode 52 disposed on a lower substrate 50, a scanning electrode 56 loaded on a dielectric layer to intersect with the data electrode 52 in perpendicular, a fluorescent material layer 60 coated the inner wall of a barrier rib 58. The dielectric layer 54 is disposed on the lower substrate 50 having the data electrode 52 thereon. If a driving voltage responding to a data signal is applied cross the data electrode 52 and the scanning electrode 56, an address discharge is caused to generate charged particles into the discharging cell. The charged particles become in a vibratory movement (or a swing movement) due to a vibratory electric field caused by a RF signal that provides across the scanning electrode 56 and the RF electrode 42. Then, the discharging gases ionize and excite continuously by the vibrate movement of the charged particles to generate continuously a discharge during a discharging period. Consequently, the PDP of the RF system has a physical effect such as a positive column having a higher discharging efficiency in a glow discharge. The RF signal to applied to the PDP of the RF system is a rectangular pulse (or a sine wave signal) having the frequency of sever MHz to sever tens MHz. However, it the charged particles and the ions are directly impacted to the barrier rib 58, the charged particle and the ion is re-combined and a light energy is converted into a thermal energy. Due to this, the light efficiency of the PDP becomes low. To prevent the leakage of the light, the polarity of the RF signal changes alternatively along with the vibrate width of the charged particle and the ion. Therefore, in the PDP using the RF discharge, the discharging efficiency enhances largely.
FIG. 3 illustrates the entire electrode configuration of the PDP having the discharging cells as shown in FIG. 2. As shown in FIG. 3, the PDP of RF system includes first to mth address electrode lines X1 to Xm arranged to oppose to column lines, first to nth scanning electrode lines Y1 to Yn arranged to oppose to row lines, and a RF electrode lines arranged in parallel with the scanning electrode lines Yl to Yn. The one ends of the RF electrode lines are connected each other. There provides the discharging cell 70 in each intersection of the address electrode lines Xl to Xm, the scanning electrode lines Y1 to Yn and RF electrode lines. The scanning electrode lines Y1 to Yn each is opposed to the RF electrode lines. The scanning electrode lines Yl to Yn and the RF electrode lines enable the RF discharge to be generated.
Such a PDP of RF system is driven by a PDP driving technique of address and display separation (ADS) system. In the PDP driving technique of ADS system, a single frame is divided into a number of sub-fields. Each sub-field is separated again into a preliminary discharging interval, an address discharging interval and a sustain discharging interval. The preliminary discharging interval and the address discharging interval become always same but the sustain discharging interval is different according to a brightness level. For example, if the single frame is divided into 8 sub-fields SF1 to SF8, the sustain discharging interval involved in each of 8 sub-fields SF1 to SF8 has a weighted value increasing at a ratio of 1, 2, 4, 8, 16, 32, 64 and 128, and the gray scale is implemented by combining the sustain discharging intervals. Also, the sub-field periods corresponding to each bit of the video data are proceeded at a fixed sequence of SF1xe2x86x92SF2xe2x86x92SF3xe2x86x92SF4 xe2x86x92SF5xe2x86x92SF6xe2x86x92SF7xe2x86x92SF8.
As described above, the PDP driven by the method of modulating discharge time becomes to display the picture depending on the total quantity of the lights emitted during each sub field period. Due to this, an integration characteristic of lights established by the PDP drive method is not identified with a visual characteristic accepted by the eyes of human. As a result, the contour noise is generated in the picture on the PDP. The contour noise appears in the shape of a black stripe or a white stripe on the PDP which displays continuously two frames (or two pictures) having gray scale levels different from each other. In other words, in the case that two gray scale levels such as 127 and 128, 63 and 64,31 and 32 and so on, which allow the emitting light patterns of two frames to be entirely different from each other, are continuously displayed, the contour noise is generated. If there are continuously displayed one frame of 127 gray level and another frame of 128 gray level, the frame of 127 gray level allows the PDP to emit lights during first sub-field SF1 to seventh sub-field SF7, while the frame of 128 gray level enables the PDP to emit lights during only eighth sub-field SF8. The difference of brightness between two frames (or two pictures) is small but a time lag between the emitting patterns of two frames is enlarged to elongate the moving distance of an eimitting light point. In this case, there is generated the black stripe on the PDP displaying continuously the two frames. Also, when there are continuously displayed one frame of 128 gray scale level and another frame of 127 gray scale level, the contour noise of the white stripe appears on the PDP displaying continuously the two frames due to the reason as described above. Such a contour noise is generated a lot more when an object of complexion moves. In other words, the contour noise appears a lot more in moving picture that the face or body of human moves. Further, when a color picture is displayed by the PDP driving technique of ADS system, it is lost a color balance by the contour noise, thereby distorting the picture displayed on the PDP. Furthermore, in the PDP driving technique of ADS system, the preliminary and address discharging intervals, which is not contributive to the picture display, are elongated relative to the sustain discharging interval contributive to the picture display. Due to this, the brightness of picture becomes low and a consumption power increases.
In FIG. 4, there is shown a conventional PDP drive apparatus of RF system including an analog/digital (A/D) converter 100 for converting an analog video signal into a video data of 8 bits and a multiplexer 110 for multiplexing the bits of video data. The conventional PDP drive apparatus of RF system further includes a frame memory 120 storing temporary the video data from the multiplexer 110 and a memory controller 130 for rearranging the video data from the frame memory 120. Also, the conventional PDP drive apparatus of RF system has a demultiplexer 140 for separating the video data from the memory controller 130 according to the bit to output the video data separated in each bit and a data driver 150 for applying a driving pulse opposite to the video data from the demultiplexer 140 to a PDP 160. The A-D converter 100 samples the analog video signal every constant period and encodes a sampled analog video signal into the video data having 8 bits. The multiplexer 110 selects the bits of video data from the A/D converter 100 and applies a selected video bit data to the frame memory 120. Then, the frame memory receives sequentially the video bit data from the multiplexer 120 and stores temporary the video bit data. To this end, the frame memory 120 has the recording capacity adapted to storage the video data for one frame. The memory controller 130 rearranges the video data from the frame memory 120 and applies toward the data driver 150. If a sub-field is divided and rearranged to minimize the contour noise, the memory controller 130 must have a complex circuit configuration. The demultiplexer 140 separates the video data from the memory controller 130 in each bit. The video data is output from the demultiplexer 140 in such a manner that there is continued pixel data bits corresponding to a sub-field. For example, if the PDP 160 is driven during the least significant sub-field having a least weighting value, a least significant bit of pixel data appears continuously in the video data to be applied to the data driver 150. The data driver 150 responds to the pixel data and drives address electrode lines on the PDP 160. Such a conventional PDP drive apparatus minimizing the contour noise makes to complex its circuit configuration.
Accordingly, it is an object of the present invention to provide a PDP drive method and apparatus which is capable of restraining the generation of contour noise and making to be high a brightness level.
Another object of the present invention provides a PDP drive apparatus capable of simplifying its circuit configuration.
In order to achieve these and other objects of the invention, a PDP drive method according to one aspect of the present invention includes steps of: allowing discharging cells on the plasma display panel to start simultaneously on a radio frequency discharge by row lines; and applying an erasing pulse corresponding to a brightness level of video to the discharging cells on a row line to erase the radio frequency discharge caused in each discharging cell on the row line.
Further, a PDP drive apparatus according to another aspect of the present invention includes steps of: scanning row lines on the plasma display panel by one every horizontal period; and providing with a data triggering signal to start in a time lag the radio frequency discharge in each discharging cell on a row line during the horizontal period.
Furthermore, a PDP drive apparatus according to another aspect of the present intention includes steps of: causing a preliminary discharge in entire picture element cells; allowing the picture element cells on any one of row lines to start simultaneously on a sustaining discharge; and erasing the sustaining discharge in each picture element on the row line in a time lag according to a gray scale.
Additionally, a PDP drive apparatus according to another aspect of the present invention includes steps of: causing a preliminary discharge in entire picture element cells; and writing selectively lag the picture element cells on any one of row lines in a time according to a gray scale to start a sustaining discharge.
A PDP drive apparatus according to another aspect of the present invention includes: converting means for converting an input video signal into a video data; storage means for storing temporally the video data for a row line, control means for rearranging the video data for a row line stored in the storage means in order of brightness level and for generating driving signals having a time lag according to the brightness level; and data driving means for applying data triggering signals corresponding to the driving signals to data electrodes on the plasma display panel.